A feasibility analysis of discharge of non-contact,once-through industrial cooling water to forested wetlands for coastal restoration in Louisiana

Louisiana has had a high rate of coastal wetland loss due mainly to the isolation of the Mississippi River from the deltaic plain. We conducted a feasibility analysis of using once-through, non-contact industrial cooling water for restoring subsiding forested wetlands in coastal Louisiana. We considered the impacts of heated water and high nutrient and sediment concentrations. River diversions introduce sediments and nutrients to stimulate the productivity and accretion of coastal wetlands. Since increases in sediments and nutrients can cause water quality problems, we analyzed the assimilative capacity of the swamp. Based on a loading rates analysis, we estimated that the following nutrient reductions would occur: 75% for NO₃, 50% for TN, 60–75% for TP, and 100% for suspended sediments. Because of the concern of impacts from heated water, it is likely that the temperature of the cooling water will have to be decreased before discharge. Altering the duration and location of the discharge are ways to minimize the impact of temperature. We recommend that a pilot study be carried out to determine the effects of heated water on the functioning of the system, the retention of sediments and nutrients, and the impacts of different discharge scenarios.     

Waterbird communities and seed biomass in managed and reference‐restored wetlands in the Mississippi Alluvial Valley

The Natural Resources Conservation Service (NRCS) commenced the Migratory Bird Habitat Initiative (MBHI) in summer 2010 after the April 2010 Deepwater Horizon oil spill in the Gulf of Mexico. The MBHI enrolled in the program 193,000 ha of private wet‐ and cropland inland from potential oil‐impaired wetlands. We evaluated waterfowl and other waterbird use and potential seed/tuber food resources in NRCS Wetland Reserve Program easement wetlands managed via MBHI funding and associated reference wetlands in the Mississippi Alluvial Valley of Arkansas, Louisiana, Mississippi, and Missouri. In Louisiana and Mississippi, nearly three times more dabbling ducks and all ducks combined were observed on managed than reference wetlands. Shorebirds and waterbirds other than waterfowl were nearly twice as abundant on managed than referenced wetlands. In Arkansas and Missouri, managed wetlands had over twice more dabbling ducks and nearly twice as many duck species than reference wetlands. Wetlands managed via MBHI in Mississippi and Louisiana contained ≥1.3 times more seed and tuber biomass known to be consumed by waterfowl than reference wetlands. Seed and tuber resources did not differ between wetlands in Arkansas and Missouri. While other studies have documented greater waterbird densities on actively than nonmanaged wetlands, our results highlighted the potential for initiatives focused on managing conservation easements to increase waterbird use and energetic carrying capacity of restored wetlands for waterbirds.     

The Value of Wetlands in Protecting Southeast Louisiana from Hurricane Storm Surges

The Indian Ocean tsunami in 2004 and Hurricanes Katrina and Rita in 2005 have spurred global interest in the role of coastal wetlands and vegetation in reducing storm surge and flood damages. Evidence that coastal wetlands reduce storm surge and attenuate waves is often cited in support of restoring Gulf Coast wetlands to protect coastal communities and property from hurricane damage. Yet interdisciplinary studies combining hydrodynamic and economic analysis to explore this relationship for temperate marshes in the Gulf are lacking. By combining hydrodynamic analysis of simulated hurricane storm surges and economic valuation of expected property damages, we show that the presence of coastal marshes and their vegetation has a demonstrable effect on reducing storm surge levels, thus generating significant values in terms of protecting property in southeast Louisiana. Simulations for four storms along a sea to land transect show that surge levels decline with wetland continuity and vegetation roughness. Regressions confirm that wetland continuity and vegetation along the transect are effective in reducing storm surge levels. A 0.1 increase in wetland continuity per meter reduces property damages for the average affected area analyzed in southeast Louisiana, which includes New Orleans, by $99-$133, and a 0.001 increase in vegetation roughness decreases damages by $24-$43. These reduced damages are equivalent to saving 3 to 5 and 1 to 2 properties per storm for the average area, respectively.     

The last 1000 years of natural and anthropogenic low-oxygen bottom-water on the Louisiana shelf, Gulf of Mexico

The relative abundance of three species of low-oxygen tolerant benthic foraminifers, the PEB index, in foraminiferal assemblages from sediment cores is used to trace the history of low-oxygen bottom-water conditions on the Louisiana shelf. Analyses of a network of box cores indicate that the modern zone of chronic seasonal hypoxia off the Mississippi Delta began to develop around 1920 and was well established by 1960. The pattern of development over the last century is consistent with the interpretation that the formation of modern chronic hypoxia is related to anthropogenic activities resulting in increased transport of nutrients to the Louisiana shelf.The PEB index in two gravity- and box core pairs (MRD05-4 and 05-6) indicates that low-oxygen bottom-water events have occurred periodically on the Louisiana Shelf for at least the last 1000 ¹⁴C years. The pre-1900 low-oxygen bottom-water events are likely caused by intervals of increased Mississippi River discharge and widespread wetland export. The PEB record in gravity cores indicates that the pre-1900 low-oxygen bottom-water events were not as well developed or as geographically extensive as the modern hypoxia zone. We conclude that the development of low-oxygen bottom-water on the Louisiana shelf is a natural process that has been negatively modified by human activities in the last 100 years.     

Coastal and marine wetlands in Gulf St. Vincent,South Australia: understanding their loss and degradation

Despite the vastness of South Australia's coastline, approximately 95% of the state's population of 1.4 million is on the Adelaide metropolitan coast of Gulf St. Vincent. The concentration of human activity around this shallow, sheltered gulf ecosystem has led to conflict and competition over the use of marine and coastal resources. The gulf supports extensive areas of ecologically significant subtidal and tidal coastal wetlands, comprising seagrass meadows, mangroves and saltmarshes, with nine wetlands having recognized national importance. The wetlands support economic activities such as commercial and recreational fishing, tourism and aquaculture, and to a lesser extent, mineral and petroleum exploration and shipping. These environments and activities are threatened by the effects of land-based urbanization, coastal development, stormwater runoff effluent and industrial discharges, and the resultant decline in water quality and food-chain contamination. Marine activities can also have adverse effects (i.e., dredging, sea-dumping, overfishing, fishing methods, oil spills, antifoulants, ballast water introductions), including the developing aquaculture industry. The continued loss and degradation of marine and coastal wetlands in the gulf is exacerbated by inadequate protection measures, lack of integrated management structures and policies, and conflict between competing user groups. Strong policies and integrated decision making based on sound information is required for the equitable and sustainable use of these wetlands. Gulf-level management of multiple-uses would limit the cumulative impacts of human use and coastal development. There is a particular need to protect areas with high conservation value and for future research and marine conservation to focus on the coastal nearshore ecosystem. High priorities are coastal and biodiversity inventories, understanding of ecological processes, linkages between coastal and offshore habitats, and coastal spatial mapping and information systems.     

Using ecotechnology to address water quality and wetland habitat loss problems in the Mississippi basin: a hierarchical approach

Human activities are affecting the environment at continental and global scales. An example of this is the Mississippi basin where there has been a large scale loss of wetlands and water quality deterioration over the past century. Wetland and riparian ecosystems have been isolated from rivers and streams. Wetland loss is due both to drainage and reclamation, mainly for agriculture, and to isolation from the river by levees, as in the Mississippi delta. There has been a decline in water quality due to increasing use of fertilizers, enhanced drainage and the loss of wetlands for cleaning water. Water quality has deteriorated throughout the basin and high nitrogen in the Mississippi river is causing a large area of hypoxia in the Gulf of Mexico adjacent to the Mississippi delta. Since the causes of these problems are distributed over the basin, the solution also needs to be distributed over the basin. Ecotechnology and ecological engineering offer the only ecologically sound and cost-effective method of solving these problems. Wetlands to promote nitrogen removal, mainly through denitrification but also through burial and plant uptake, offer a sound ecotechnological solution. At the level of the Mississippi basin, changes in farming practices and use of wetlands for nitrogen assimilation can reduce nitrogen levels in the River. There are additional benefits of restoration of wetland and riverine ecosystems, flood control, reduction in public health threats, and enhanced wildlife and fisheries. At the local drainage basin level, the use of river diversions in the Mississippi delta can address both problems of coastal land loss and water quality deterioration. Nitrate levels in diverted river water are rapidly reduced as water flows through coastal watersheds. At the local level, wetlands are being used to treat municipal wastewater. This is a cost-effective method, which results in improved water quality, enhanced wetland productivity and increased accretion. The problems in the Mississippi basin serves as an example for other watersheds in the Gulf of Mexico. This is especially important in Mexico, where there is a strong need for economical solutions to ecological problems. The Usumacinta delta-Laguna de Terminos regional ecosystem is an example where ecotechnological approaches offer realistic solutions to environmental problems.     

Influence of hurricanes on coastal ecosystems along the northern Gulf of Mexico

Available literature indicates that hurricanes do not generally produce long-term detrimental impacts to unmodified coastal systems and that they often provide net benefits along the U.S. Gulf Coast. While there is normally initial erosion from hurricanes, they also often result in a large influx of inorganic sediments, creating new wetlands and contributing to the maintenance of existing wetlands. The formation of washover deposits is disastrous where cultural development has occurred, but in natural areas these deposits are part of the natural cycle of shoreline development and contribute to habitat diversity and productivity. Abundant rainfall typically associated with hurricanes often results in large increases of sediment and nutrient inputs into coastal estuaries, leading to both short-term and long-term increases in productivity. Rainfall during tropical disturbances accounts for a significant part of total precipitation along the northern gulf. The immediate impact of hurricanes may be to reduce populations of some species but these populations generally recover rapidly. Overall, productivity in natural systems seems to be increased by periodic hurricanes. Hurricane impacts are often severe and long lasting in wetlands that have been modified by human impacts such as semi- or complete impoundments.     

Global genetic analysis reveals the putative native source of the invasive termite,Reticulitermes flavipes,in France

Biological invasions are recognized as a major threat to both natural and managed ecosystems. Phylogeographic and population genetic analyses can provide information about the geographical origins and patterns of introduction and explain the causes and mechanisms by which introduced species have become successful invaders. Reticulitermes flavipes is a North American subterranean termite that has been introduced into several areas, including France where introduced populations have become invasive. To identify likely source populations in the USA and to compare the genetic diversity of both native and introduced populations, an extensive molecular genetic study was undertaken using the COII region of mtDNA and 15 microsatellite loci. Our results showed that native northern US populations appeared well differentiated from those of the southern part of the US range. Phylogenetic analysis of both mitochondrial and nuclear markers showed that French populations probably originated from southeastern US populations, and more specifically from Louisiana. All of the mtDNA haplotypes shared between the United States and France were found in Louisiana. Compared to native populations in Louisiana, French populations show lower genetic diversity at both mtDNA and microsatellite markers. These findings are discussed along with the invasion routes of R. flavipes as well as the possible mechanisms by which French populations have evolved after their introduction.     

Drought‐induced saltwater incursion leads to increased wetland nitrogen export

Coastal wetlands have the capacity to retain and denitrify large quantities of reactive nitrogen (N), making them important in attenuating increased anthropogenic N flux to coastal ecosystems. The ability of coastal wetlands to retain and transform N is being reduced by wetland losses resulting from land development. Nitrogen retention in coastal wetlands is further threatened by the increasing frequency and spatial extent of saltwater inundation in historically freshwater ecosystems, due to the combined effects of dredging, declining river discharge to coastal areas due to human water use, increased drought frequency, and accelerating sea‐level rise. Because saltwater incursion may affect N cycling through multiple mechanisms, the impacts of salinization on coastal freshwater wetland N retention and transformation are not well understood. Here, we show that repeated annual saltwater incursion during late summer droughts in the coastal plain of North Carolina changed N export from organic to inorganic forms and led to a doubling of annual NH₄⁺ export from a 440 hectare former agricultural field undergoing wetland restoration. Soil solution NH₄⁺ concentrations in two mature wetlands also increased with salinization, but the magnitude of increase was smaller than that in the former agricultural field. Long‐term saltwater exposure experiments with intact soil columns demonstrated that much of the increase in reactive N released could be explained by exchange of salt cations with sediment NH₄⁺. Using these findings together with the predicted flooding of 1661 km² of wetlands along the NC coast by 2100, we estimate that saltwater incursion into these coastal areas could release up to 18 077 Mg N, or approximately half the annual NH₄⁺ flux of the Mississippi River. Our results suggest that saltwater incursion into coastal freshwater wetlands globally could lead to increased N loading to sensitive coastal waters.     

Seasonal changes in pyrethroid resistance in tarnished plant bug (Heteroptera: Miridae) populations during a three-year period in the delta area of Arkansas, Louisiana, and Mississippi

Tarnished plant bugs, Lygus lineolaris (Palisot de Beauvois), were collected from weeds at 71 locations in the delta of Arkansas, Louisiana, and Mississippi and tested with a discriminating dose bioassay for pyrethroid resistance in the spring (April-May) and again at the same locations in the fall (September-October) in 1995-1997. Percentage of mortality in the discriminating dose bioassay declined significantly (pyrethroid-resistance increased) from spring to fall by an average 18.7, 21.3, and 21.7% in Arkansas, Louisiana, and Mississippi, respectively. Pyrethroid resistance declined significantly by 26.3% from the fall of 1995 to the spring of 1996 in Mississippi, but did not significantly decline in Arkansas (4.1%) and Louisiana (13.2%). Significant decreases in resistance occurred in all 3 states from the fall of 1996 to the spring of 1997 (17.1, 38.3, and 29.8% in Arkansas, Louisiana, and Mississippi, respectively). Plant bugs from 2 locations (Indianola, MS, and Wainwright, LA) had multiple insecticide resistance to a carbamate, 2 pyrethroid, and 4 organophosphorus insecticides. However, resistance to the organophosphate acephate in plant bugs from both locations was not significant. Possible causes for the significant increases and declines in resistance from season to season are discussed.     

Landscape-Scale Analysis of Wetland Sediment Deposition from Four Tropical Cyclone Events

Hurricanes Katrina, Rita, Gustav, and Ike deposited large quantities of sediment on coastal wetlands after making landfall in the northern Gulf of Mexico. We sampled sediments deposited on the wetland surface throughout the entire Louisiana and Texas depositional surfaces of Hurricanes Katrina, Rita, Gustav, and the Louisiana portion of Hurricane Ike. We used spatial interpolation to model the total amount and spatial distribution of inorganic sediment deposition from each storm. The sediment deposition on coastal wetlands was an estimated 68, 48, and 21 million metric tons from Hurricanes Katrina, Rita, and Gustav, respectively. The spatial distribution decreased in a similar manner with distance from the coast for all hurricanes, but the relationship with distance from the storm track was more variable between events. The southeast-facing Breton Sound estuary had significant storm-derived sediment deposition west of the storm track, whereas sediment deposition along the south-facing coastline occurred primarily east of the storm track. Sediment organic content, bulk density, and grain size also decreased significantly with distance from the coast, but were also more variable with respect to distance from the track. On average, eighty percent of the mineral deposition occurred within 20 km from the coast, and 58% was within 50 km of the track. These results highlight an important link between tropical cyclone events and coastal wetland sedimentation, and are useful in identifying a more complete sediment budget for coastal wetland soils.     

Adrenal Gland and Lung Lesions in Gulf of Mexico Common Bottlenose Dolphins (Tursiops truncatus) Found Dead following the Deepwater Horizon Oil Spill

A northern Gulf of Mexico (GoM) cetacean unusual mortality event (UME) involving primarily bottlenose dolphins (Tursiops truncatus) in Louisiana, Mississippi, and Alabama began in February 2010 and continued into 2014. Overlapping in time and space with this UME was the Deepwater Horizon (DWH) oil spill, which was proposed as a contributing cause of adrenal disease, lung disease, and poor health in live dolphins examined during 2011 in Barataria Bay, Louisiana. To assess potential contributing factors and causes of deaths for stranded UME dolphins from June 2010 through December 2012, lung and adrenal gland tissues were histologically evaluated from 46 fresh dead non-perinatal carcasses that stranded in Louisiana (including 22 from Barataria Bay), Mississippi, and Alabama. UME dolphins were tested for evidence of biotoxicosis, morbillivirus infection, and brucellosis. Results were compared to up to 106 fresh dead stranded dolphins from outside the UME area or prior to the DWH spill. UME dolphins were more likely to have primary bacterial pneumonia (22% compared to 2% in non-UME dolphins, P = .003) and thin adrenal cortices (33% compared to 7% in non-UME dolphins, P = .003). In 70% of UME dolphins with primary bacterial pneumonia, the condition either caused or contributed significantly to death. Brucellosis and morbillivirus infections were detected in 7% and 11% of UME dolphins, respectively, and biotoxin levels were low or below the detection limit, indicating that these were not primary causes of the current UME. The rare, life-threatening, and chronic adrenal gland and lung diseases identified in stranded UME dolphins are consistent with exposure to petroleum compounds as seen in other mammals. Exposure of dolphins to elevated petroleum compounds present in coastal GoM waters during and after the DWH oil spill is proposed as a cause of adrenal and lung disease and as a contributor to increased dolphin deaths.     

An update on the distribution of Parelaphostrongylus tenuis in the southeastern United States

An update is presented on the distribution of the meningeal worm (Parelaphostrongylus tenuis) of white-tailed deer (Odocoileus virginianus) in the southeastern United States. The parasite is widely distributed and common in all or much of Arkansas, Kentucky, Louisiana, Maryland, North Carolina, Tennessee, Virginia and West Virginia. It is also common in the northern half of Alabama and Georgia. In contrast, it is rare or absent along the Atlantic and Gulf coastal plains of Alabama, Georgia, Mississippi and South Carolina. It has been collected from a single deer in Florida.     

Genetic differentiation, structure, and a transition zone among populations of the pitcher plant moth Exyra semicrocea: implications for conservation

Pitcher plant bogs, or carnivorous plant wetlands, have experienced extensive habitat loss and fragmentation throughout the southeastern United States Coastal Plain, resulting in an estimated reduction to <3% of their former range. This situation has lead to increased management attention of these habitats and their carnivorous plant species. However, conservation priorities focus primarily on the plants since little information currently exists on other community members, such as their endemic arthropod biota. Here, we investigated the population structure of one of these, the obligate pitcher plant moth Exyra semicrocea (Lepidoptera: Noctuidae), using mitochondrial cytochrome c oxidase subunit I (COI) gene sequences. Examination of 221 individuals from 11 populations across eight southeastern US states identified 51 unique haplotypes. These haplotypes belonged to one of two divergent (～1.9-3.0%) lineages separated by the Mississippi alluvial plain. Populations of the West Gulf Coastal Plain exhibited significant genetic structure, contrasting with similarly distanced populations east of the Mississippi alluvial plain. In the eastern portion of the Coastal Plain, an apparent transition zone exists between two regionally distinct population groups, with a well-established genetic discontinuity for other organisms coinciding with this zone. The structure of E. semicrocea appears to have been influenced by patchy pitcher plant bog habitats in the West Gulf Coastal Plain as well as impacts of Pleistocene interglacials on the Apalachicola-Chattahoochee-Flint River Basin. These findings, along with potential extirpation of E. semicrocea at four visited, but isolated, sites highlight the need to consider other endemic or associated community members when managing and restoring pitcher plant bog habitats.     

Implications of global climatic change and energy cost and availability for the restoration of the Mississippi delta

Over the past several thousand years, inputs from the Mississippi River formed the Mississippi delta, an area of about 25,000 km². Over the past century, however, there has been a high loss of coastal wetlands of about 4800 km². The main causes of this loss are the near complete isolation of the river from the delta, mostly due to the construction of flood control levees, and pervasive hydrological disruption of the deltaic plain. There is presently a large-scale State-Federal program to restore the delta that includes construction of water control structures in the flood control levees to divert river water into deteriorating wetlands and pumping of dredged sediment, often for long distances, for marsh creation. Global climate change and decreasing availability and increasing cost of energy are likely to have important implications for delta restoration. Coastal restoration efforts will have to be more intensive to offset the impacts of climate change including accelerated sea level rise and changes in precipitation patterns. Future coastal restoration efforts should also focus on less energy-intensive, ecologically engineered management techniques that use the energies of nature as much as possible. Diversions may be as important for controlling salinity as for providing sediments and nutrients for restoring coastal wetlands. Energy-intensive pumping-dredged sediments for coastal restoration will likely become much more expensive in the future.     

Evaluating wetland losses with hydric soils

A study was conducted to determine if surveys of hydric soils could be used as a historic baseline to estimate wetland losses. Soils were digitized from county soil surveys and wetlands were digitized from National Wetlands Inventory (NWI) maps for two adjacent coastal counties in North Carolina. The two counties were located on the lower Atlantic Coastal Plain and have extensive areas of hydric soils, as much as 96% of the land surface area. Using hydric soils from soil surveys and wetlands from NWI maps, wetland losses since settlement were calculated to be 65% for Washington County and 38% for Tyrrell County. The NWI wetlands were compared to a mid-1950s wetlands survey to determine recent wetland losses. A large percentage of the wetland losses occurred between 1950 and 1980 for Washington County compard to Tyrrell County. Wetland losses for both counties occurred primarily on mineral hydric soils and the current wetlands distribution corresponded well with the distribution of organic soils.     

Demographic Clusters Identified within the Northern Gulf of Mexico Common Bottlenose Dolphin (Tursiops truncates) Unusual Mortality Event: January 2010 - June 2013

A multi-year unusual mortality event (UME) involving primarily common bottlenose dolphins (Tursiops truncates) was declared in the northern Gulf of Mexico (GoM) with an initial start date of February 2010 and remains ongoing as of August 2014. To examine potential changing characteristics of the UME over time, we compared the number and demographics of dolphin strandings from January 2010 through June 2013 across the entire GoM as well as against baseline (1990-2009) GoM stranding patterns. Years 2010 and 2011 had the highest annual number of stranded dolphins since Louisiana’s record began, and 2011 was one of the years with the highest strandings for both Mississippi and Alabama. Statewide, annual numbers of stranded dolphins were not elevated for GoM coasts of Florida or Texas during the UME period. Demographic, spatial, and temporal clusters identified within this UME included increased strandings in northern coastal Louisiana and Mississippi (March-May 2010); Barataria Bay, Louisiana (August 2010-December 2011); Mississippi and Alabama (2011, including a high prevalence and number of stranded perinates); and multiple GoM states during early 2013. While the causes of the GoM UME have not been determined, the location and magnitude of dolphin strandings during and the year following the 2010 Deepwater Horizon oil spill, including the Barataria Bay cluster from August 2010 to December 2011, overlap in time and space with locations that received heavy and prolonged oiling. There are, however, multiple known causes of previous GoM dolphin UMEs, including brevetoxicosis and dolphin morbillivirus. Additionally, increased dolphin strandings occurred in northern Louisiana and Mississippi before the Deepwater Horizon oil spill. Identification of spatial, temporal, and demographic clusters within the UME suggest that this mortality event may involve different contributing factors varying by location, time, and bottlenose dolphin populations that will be better discerned by incorporating diagnostic information, including histopathology.     

滨海湿地消浪服务空间分布特征——以上海市崇明岛为例

全球气候变化增加了滨海地区遭受侵蚀、风暴潮等灾害的风险,利用自然湿地的消浪功能增强海岸防护是当前研究的热点,但目前对消浪服务的空间分布评估研究相对匮乏。以上海市崇明岛环岛滨海湿地为例,结合GIS与Kobayashi指数形式波高衰减模型评估常规状态下湿地消浪服务的空间分布特征。结果显示,大、小潮升条件下,崇明环岛湿地消波的平均高度分别为0.94、0.54 m与效度分别为83.6%、60.4%,消波高度的空间分布表现为南岸小于北岸,消波效度的空间分布在小潮升时与消波高度相似,而大潮升时南岸的消波效度有明显提升。物理环境与生物因素空间分布及其相互作用的异质性,导致消浪服务的空间分布也具有空间异质性。实际参与消波的断面宽度与不同景观消波服务的评估结果表明,一个断面的所有景观并非都参与到消浪过程中,即使在大潮升时期,不同岸段景观的平均参与度不足71%。潮高与波高的增加并不会使参与消波的景观规模成对应比例的增加,说明消波服务在空间上具有明显的非线性特征。研究可为滨海湿地生态修复空间规划、基于生态系统的海岸带管理、自然资本核算提供科技支撑。     

Bearing Witness: Assumptions, Realities, and the Otherizing of Katrina

As post-Katrina rebuilding of Louisiana and Mississippi proceeds, we should heed the lessons from anthropologists and others studying aid and development in other parts of the world who point out that aid is often predicated on poorly examined assumptions about beneficiaries and local conditions. Hence, as the recovery after Katrina continues, assumptions about the U.S. South and about poverty, race, and class in the United States must be exposed and examined as well as assumptions about disaster victims and relief. Drawing on personal experiences, I examine here some of the assumptions with which I operated as a small group of friends and I organized an unofficial relief team to provide whatever aid we could to people on the Mississippi Gulf coast in the first few weeks after Hurricane Katrina. I recount the disconnections between my assumptions and the local conditions as relayed by Katrina survivors or that members of the team and I witnessed firsthand.     

Land use and land cover change analysis in predominantly man-made coastal wetlands: towards a methodological framework

In areas with a long history of human occupation, coastal wetlands have undergone extensive modification to accommodate extractive activities as salt-extraction and aquaculture. These man-made wetlands maintain some of the ecological functions of natural wetlands in spite of their artificial character: their suitability as complimentary waterbird habitat is well documented. In cases of wetlands composed of mixed natural and man-made areas, similarities in substrate-vegetation-water compositions may pose challenges in the applicability of remote sensing and GIS techniques for the study of landscape changes, requiring tailor-made, case-specific methods. We explored this supposition by testing these techniques for the study of the Bahia de Cadiz Nature Park (Spain). Using Landsat imagery spanning the 1985–2011 period, natural and man-made marsh areas were classified separately and results merged to produce land cover classification maps. Different change dynamics were observed for the natural and man-made areas, the latter exhibiting prominent changes, including widespread vegetative succession. Further, through the overlay of ancillary land use data for 2011, an integrated land use and cover map was produced for this year. Different scenarios arising from the abandonment of extractive activity and structural negligence were highlighted. Furthermore, a methodological framework for the classification of predominantly man-made wetlands was designed. The method is cost-effective and open for integration of additional datasets, and is considered a beneficial input to conservation and land use management. Its applicability for monitoring of landscape change not only pertains to the study area, but also extends to other coastal wetland areas of a similar nature.